[p.1]

Hi. This is my UDF:

#include "udf.h"
#define uinf 1.75
#define d 6

DEFINE_ADJUST(uu, domain)
{
Thread *t;
cell_t c;

thread_loop_c(t, domain)
{
begin_c_loop(c, t)
{
real mu_t = C_MU_T(c, t); /*Eddy Viscosity*/
real k = C_K(c, t); /*Turbulence Kinetic Energy*/
real ux = C_U_G(c, t)[0]; /*du/dx*/

C_UDSI(c, t, 0) = 2 * mu_t*ux - (2 / 3)*k;

C_UDMI(c, t, 3) = -C_UDSI_G(c, t, 0)[0] / (uinf*uinf*d);
}
end_c_loop(c, t)
}
}


I have to get the contours of the UDM, so I put "uu" in "User-Defined Function Hooks" but Fluent crash. If I don't put "uu" in "User-Defined Function Hooks" Fluent run the calculation but the value of my UDM is 0.
How can I solve it?

[AlexanderZ]

you should put "uu" in "User-Defined Function Hooks" to make it executed.
why do you use scalar in your code? C_UDSI(c, t, 0)

most likely, you didn't allocate memories for user defined scalars and/or for user defined memory

also

In order to retain the
gradient data (when you want to set up user-defined scalar transport equations, for example), you can
prevent the solver from freeing up memory by issuing the text command solve/set/expert and
then answering yes to the question, “Keep temporary solver memory from being freed?”

you may try this code, allocate 2 memory locations in FLUENT GUI

#include "udf.h"
#define uinf 1.75
#define d 6

DEFINE_ADJUST(uu, domain)
{
Thread *t;
cell_t c;
real mu_t; /*Eddy Viscosity*/
real k; /*Turbulence Kinetic Energy*/
real ux; /*du/dx*/

thread_loop_c(t, domain)
{
begin_c_loop(c, t)
{
mu_t = C_MU_T(c, t); /*Eddy Viscosity*/
k = C_K(c, t); /*Turbulence Kinetic Energy*/
ux = C_U_G(c, t)[0]; /*du/dx*/

C_UDMI(c, t, 0) = 2 * mu_t*ux - (2 / 3)*k;
C_UDMI(c, t, 1) = (2 * mu_t*ux - (2 / 3)*k) / (uinf*uinf*d);
}
end_c_loop(c, t)
}
}

[p.1]

Originally Posted by AlexanderZ

why do you use scalar in your code? C_UDSI(c, t, 0)
[/CODE]

Thank you, I use C_UDSI(c,t,0) because I have to get the gradient of this UDS, in fact in C_UDMI I have C_UDSI_G. In your UDF there isn't the gradient, right?